-rac_signalForSelector:, -objectPassingTest:, miscellaneous fixes

Add -all:, fix commands never completing, add -rac_didDeallocSignal

Fix -deliverOn: space usage, asynchronous -scheduleRecursiveBlock:

Move NSButton.rac_command to NSControl, add rac_textSignal

Added folding methods and -[RACSignal executeCommand:]

Fix -toProperty:onObject: disposal

Threading bug fixes, new waiting methods, fixed -switchToLatest

Fix RACCommand crash on ARM, added -not, fixes to RACStringSequence

Initial stable API release

RACTupleUnpack(), crazy amounts of documentation